1. Field of the Invention
This invention relates to a process for the gasification of carbon-containing raw materials, especially fossil fuels and more particularly coal, coke, crude oil and fractions of the oil, by treating the material with H.sub.2 O in a reaction space in the presence of a catalytically active salt.
2. Description of the Prior Art
A process of the above type is described in pages 137 to 139 of "Energy Research", Vol. 4, 137-147 (1980). According to this process an aqueous solution of potassium carbonate is sprayed as a catalytically active salt onto a raw material which consists of ground coal. The coal is then dried and fed into the reaction space of a fluidized bed reactor. In addition, H.sub.2 O in the form of steam is conducted into the fluidized bed reactor so that, at a reaction pressure of 35 bars and a reaction temperature of 700.degree. C., there occurs (a) a gasification of carbon to carbon monoxide and hydrogen, (b) a conversion of carbon monoxide to carbon dioxide and hydrogen, and (c) a reduction of CO to methane and water, according to the following overall reaction equations:
(a) C+H.sub.2 O=CO+H.sub.2 PA1 (b) CO+H.sub.2 O=CO.sub.2 +H.sub.2 PA1 (c) CO+3H.sub.2 =CH.sub.4 +H.sub.2 O
The potassium carbonate used as catalyst not only accelerates the gasification (a), but also regulates the equilibrium of the conversion (b) and of the reduction (c).
The product gases, namely hydrogen, carbon monoxide, carbon dioxide and methane, and also the water which has not been converted, leave the fluidized bed reactor. From this mixture carbon dioxide can be first removed, for example by washing with monoethanolamine. From the remaining mixture methane can be separated by low temperature distillation. The remaining hydrogen/carbon monoxide mixture can be mixed with steam again, heated to the reaction temperature and recycled to the fluidized bed reactor.